Switching between two communication modes in a WLAN

ABSTRACT

Method and system for switching a network application operating in a first communication mode to a second mode within a wireless local area network, comprising: judging whether mobile nodes are neighboring according to location information; when nodes are neighboring inquiring whether mobile nodes want to switch to second mode to run network applications; when all mobile nodes agree to switch to second mode, downloading and installing network application provided by the application server to one of the mobile nodes; configuring each of the mobile nodes with the communication parameters under the second mode; and switching all mobile nodes to the second communication mode to continue the previous network application. The invention dynamically switches between Infrastructure mode and Ad-hoc mode to balance system resources, improve QoS, reduce the communication traffic, waiting time and the cost of the users, and increase the income of the provider of the network service.

This application is a continuation of, and claims priority to,application Ser. No. 11/377,484, filed on Mar. 16, 2006, now U.S. Pat.No. 7,899,017; United States patent claims priority to Chineseapplication 200510004027.9, with a priority date of Jan. 5, 2005.

FIELD OF THE INVENTION

The present invention is generally related to wireless networkcommunication technology. More particularly, the present invention isrelated to the method and system of on-demand switching between twodifferent types of communication mode in the wireless local network,i.e. Infrastructure Mode and Ad-hoc Mode.

BACKGROUND OF THE INVENTION

In network application, when the transport media is changed from wire toradio waves, the communication protocol 802.11 (i.e. Wireless LocalNetwork WLAN) is used, which was defined by IEEE. Protocol 802.11technologies provide high speed wireless connection to the network. The802.11 standard defines two network modes: infrastructure mode andAd-hoc mode. In infrastructure mode, a mobile user accesses network andcommunicates with other mobile users through access point (AP); while inAd-hoc mode, the mobile users communicate with each other in a peer topeer mode. To be more specific, the computer users normally using WLANcan work in two modes: infrastructure mode and Ad-hoc mode.Infrastructure mode is used for mobile nodes i.e. the wireless devicesof the mobile users can access the public network through access points,while Ad-hoc mode is used for a plurality of neighboring mobile nodes tocommunicate with each other directly.

Referring to FIG. 1, it shows a wireless local network communicating inan infrastructure mode. In this infrastructure mode, each mobile node(or called as wireless node) communicates with other mobile nodes orfixed nodes of the network through the access point (AP). The accesspoint is used as a bridge, transponder, gateway or firewall between themobile nodes and the wired network. That is to say, in thisinfrastructure mode, the AP which is a part of the wired networkinfrastructure is provided as the bridge between the wireless and thewired LAN and through which the mobile nodes can communicate withInternet. FIG. 1 schematically describes an example of the mobile node,i.e. a laptop computer communicates in the infrastructure mode. Thoughthere only shows one mobile node in FIG. 1, it should be understood thatthere can be many mobile nodes that communicate simultaneously in theinfrastructure mode; in addition, the mobile node in FIG. 1 is a laptopcomputer, however, it should be understood that the mobile nodes can beother wireless devices, including and not limited to, mobile phones,Personal Digital Assistant (PDA), Palm computer, etc. The mobile node,such as the laptop in FIG. 1, normally has a wireless card with whichthe mobile node can exchange information with other wireless devicesthrough AP, thus the wireless communication among mobile nodes can berealized. AP itself needs a static IP address, and it can support theaccess of limited number of mobile nodes within its working range(different AP has different working range, the relevant user manual mayprovide such data, i.e. 30 meters). The working range of AP is calledBasic Service Set (BSS) and all the users of the AP share the same BSSID.

In most wireless local networks, normally, at least one authenticationserver is used as shown in FIG. 1. The authentication server is used toauthenticate the ID of the user on the mobile node. The authenticationserver can also obtain a lot of information about the user, such as theIP address of the user, the AP through which the user access thenetwork, the time when the user access the network and the time when theuser leaves, etc.

If more wireless devices need to be supported in the infrastructurenetwork mode, the following work pattern can be used. Here, multiple APsconnect together and share the same authentication server as shown inFIG. 2. FIG. 2 schematically shows an exemplary of an Extended ServiceSet (ESS) made up of a plurality of APs in the infrastructure mode.Here, each AP has its relevant BSS and all APs' working ranges composean Extended Service Set (ESS), and the mobile nodes sharing the same ESSID can roam freely among these APs without losing network connections.

When the mobile node is set to work in the infrastructure mode, it usesa static or dynamic IP address. The authentication server can locate themobile node according to its relevant AP and IP address.

In Ad-hoc mode, the mobile nodes can communicate with each otherdirectly. That is to say that the mobile node communicates with othermobile nodes in a peer to peer mode within its RF range instead ofcommunicating through the inter-medium node which is the access point ofinfrastructure mode. When users are very close to each other, Ad-hocmode connection is very useful for communication. FIG. 3 is the diagramof the communication in Ad-hoc mode. FIG. 3 schematically shows fourneighboring mobile nodes, i.e. four laptop computers communicating inAd-hoc mode. Here, each mobile node is equipped with a wireless cardwith which two or more mobile nodes can communicate with each other atthe peer to peer level and said mobile nodes share a given cell coveragearea. When the mobile nodes are set in Ad-hoc mode, they need to be setwith static IP addresses and all the mobile nodes which communicate witheach other belong to the same working group. Similarly, they also sharethe same ESS ID.

In the prior art, infrastructure mode is commonly used in office,hot-spot, while Ad-hoc mode is often used in the places without networkinfrastructure, smaller areas, or close distance communication, i.e. thecommunication among the exploration workers during the resourceexploration in high mountains; as well as communication among rescueworker in the after earthquake or communication among colleagues at ameeting in a meeting room, etc. More specifically when the networkresource is limited, as compared with infrastructure mode, Ad-hoc modecan save a great amount of resources when the communication is limitedto certain local area.

In the prior art, i.e. the US patent application US2003/0054818A1entitled as “SYSTEM AND METHOD FOR CONCURRENT OPERATION OF A WIRELESSDEVICE IN TWO DISJOINT WIRELESS NETWORKS” discloses a dual mode wirelessdevice. It can operate in two wireless network modes, i.e.infrastructure mode and Ad-hoc mode. The dual mode device has a wirelesscontroller inserted in the wireless card which has two virtual wirelessnetwork adaptors thereon. One is for infrastructure mode and the otherfor Ad-hoc mode. The wireless control driver controls the switchingbetween the two network modes. This patent application is also relatedto the switching between infrastructure mode and Ad-hoc mode. It is theswitching performed on the network facilities in which the controllercontrols the two network modes within said one device while the twomodes are independent to each other. Each mode accesses its ownapplication program and does not know other's sessions of accessingapplications and communicates separately. It can be seen from thisapplication that the technology disclosed by this patent application cannot realize accessing the same application and sharing the session foraccessing the application when the two communication modes areautomatically switched. Therefore, a method and device are neededthrough which users can access the application with the same sessionwhen the two communication modes are switched automatically. This willsave the users' network resources and cost when accessing the networkapplications.

In addition, the US patent application US2004/0063458A1 entitled“WIRELESS LAN COMMUNICATION SYSTEM” discloses a wireless communicationsystem that supports a dual-mode switching and also realizes theautomatic switching between infrastructure mode and Ad-hoc mode. Thewireless communication system of that patent application judges whetherit is necessary to switch from infrastructure to Ad-hoc modes bymonitoring data pack. If data pack marked with target address isdetected, the channel search will be conducted. When suitable channel isfound, the communication mode will be switched to Ad-hoc mode andestablish connection between the source and the target. In this system,the source or target workstation is made up of date transfer receiver,wireless interface, data pack header analyzer, channel search engine,switch controller and data cache. When it is necessary to switch fromAd-hoc mode back to infrastructure mode, one party of the source andtarget workstation of the connection which is already established willsend a data pack requesting to switch back to infrastructure mode. Thenthe two parties will switch back to infrastructure mode. From the abovementioned description of the patent application, the patent applicationmainly focus on that the network layer parses the data pack and judgeswhether the target can use Ad-hoc mode or not to switch communicationchannels. It judges whether to switch or not by adding the header ofdata pack as identity and it is mainly used for data transfer betweentwo points. Meanwhile, it requires that the two sides of thecommunication should have the capacity of workstations. Comparativelyspeaking, this will make the switching between the two modes morecomplicated. Therefore, a more flexible technical solution is needed toautomatically switch between the two modes.

In addition, according to the usage of the wireless local networknowadays, some popular network applications such as network gaming,network chatting, e-meeting, etc., usually operate in infrastructuremode. In certain cases, as a result of the access by too many mobilenodes in infrastructure mode, the network resources get scarce and theoperation efficiency is very poor; under that circumstance, if part ofthe users can be switched to Ad-hoc mode, the resources of the wholenetwork will be balanced. As a matter of fact, in the application of thewireless local network nowadays, when the resources in infrastructuremode are restricted, it is seldom considered to balance the networkresource by switching the network applications from infrastructure modeto Ad-hoc mode.

Consider the following scenario, the airport ABC provides network gamingand chatting platform only based on infrastructure mode for thepassengers waiting for their airplanes. The Airport ABC charges thepassengers' fee according to their network usage or connection time.Most of passengers would like to play network games using a mobile node,such as laptop, PDA, which can access WLAN. But there comes the issue ofresource restriction. For example, all the APs in the airport can onlysupport about 200 concurrent users, but there may be more than 400 userswanting to play the network game at the same time. With the current WLANinfrastructure, the principle of “First come, first serve” has to beapplied. Consequently, half of the users fail to connect to the network.This causes the low quality of service (QoS) and depresses customersatisfaction. To solve this issue, one way is to add more APs to enlargethe capacity but it will raise the investment (meanwhile per unit costof connection is increased and potential users may be lost). Also it'snot a long-term solution since the number of users/connections ischanging. In infrastructure mode, resource allocation can't bedynamically changed according to variation of connections.

SUMMARY OF THE INVENTION

To solve the above mentioned problems, an aspect of the presentinvention is to provide methods, apparatus and systems which candynamically switch between two communication modes of the wireless localnetwork, i.e. infrastructure mode and Ad-hoc mode to optimize andbalance network resources.

Another aspect of the present invention is according to the variation ofconnection of the mobile nodes, to dynamically and real-time change thecommunication mode of the mobile nodes in the WLAN, switching real-timefrom infrastructure mode to Ad-hoc mode or dynamically switching fromAd-hoc mode back to infrastructure mode.

Another aspect of the present invention is in that when the mobile nodesswitch from infrastructure to Ad-hoc mode to optimize network resources,the application the mobile node is accessing will not be affected; whenthe application can not be accessed by the mobile nodes in Ad-hoc mode,the mobile nodes can switch back to infrastructure mode and return tothe previous application interface.

Another aspect of the present invention is in that, at the applicationlevel, while the communication channel is switched the applicationprogram can be maintained to continue to operate and at the same timecommunication among many points can be achieved.

Still another aspect of the present invention is to put forward a methodand system that can switch between two communication modes based on thejudgment of the application in operation, location of users and thestatus of the network resources.

Still another aspect of the present invention is to provide the mobilenodes with software that can be downloaded from the application server.Through running the software on the wireless devices of the mobileusers, the wireless devices of the mobile users can be switched betweenthe two communication modes conveniently and flexibly.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages as well as benefits of the present inventionwill be more evident and striking through the detailed description ofthe preferable embodiments with reference to the drawings forming a partof the disclosure herein. The description of the embodiments withreference to the drawings makes it easy to have a better understandingof the present invention, in which:

FIG. 1 is a diagram schematically illustrating that the wireless localnetwork communicates in an infrastructure mode;

FIG. 2 is a diagram illustrating that multiple APs make up an extendedservice set in an infrastructure mode;

FIG. 3 is a diagram illustrating the communication in Ad-hoc mode;

FIG. 4 illustrates an example of the system parameters sub-page of Cisco340 series wireless card property;

FIG. 5 illustrates network a security page of a Cisco 340 wireless cardproperty;

FIG. 6 illustrates a configuration page of a network parameter “InternetProtocol (TCP/IP) Property”;

FIG. 7 is a block diagram illustrating the components implementing themethod of the present invention;

FIG. 8 is a flow diagram illustrating the switching from infrastructuremode to Ad-hoc mode and continuing previous application according to thepresent invention;

FIG. 9 is a flow diagram illustrating operations carried out by theapplication agent in the application server; and

FIG. 10 is a flow diagram illustrating the operations carried out by theclient agent in the client terminal of the mobile nodes.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides apparatus, methods and systems todynamically switch between two communication modes of a wireless localnetwork, i.e. infrastructure mode and Ad-hoc mode to optimize andbalance network resources.

The present invention also provides according to the variation ofconnection of the mobile nodes, to dynamically and real-time change thecommunication mode of the mobile nodes in the WLAN, switching real-timefrom infrastructure mode to Ad-hoc mode or dynamically switching fromAd-hoc mode back to infrastructure mode.

The present invention also provides when the mobile nodes switch frominfrastructure to Ad-hoc mode to optimize network resources, theapplication the mobile node is accessing will not be affected; when theapplication can not be accessed by the mobile nodes in Ad-hoc mode, themobile nodes can switch back to infrastructure mode and return to theprevious application interface.

The present invention also provides at the application level, while thecommunication channel is switched the application program can bemaintained to continue to operate and at the same time communicationamong many points can be achieved.

The present invention also provides to put forward a method and systemthat can switch between two communication modes based on the judgment ofthe application in operation, location of users and the status of thenetwork resources.

The present invention also provides the mobile nodes with software thatcan be downloaded from the application server. Through running thesoftware on the wireless devices of the mobile users, the wirelessdevices of the mobile users can be switched between the twocommunication modes conveniently and flexibly.

For this end, the present invention provides a method for switching anetwork application operating in a first communication mode to a secondcommunication mode within a wireless local area network, wherein aplurality of mobile nodes access the network through at least one accesspoint and communicate with at least one application server to obtainvarious network applications provided by said application server in thefirst communication mode; and a plurality of neighboring mobile nodescan communicate with each other directly in the second communicationmode; the method comprising the steps of: when the plurality of mobilenodes accessing the application server on the network through the accesspoints and running the same network application provided by saidapplication server in the first communication mode, judging whether theplurality of mobile nodes are neighboring according to the locationinformation of said mobile nodes; sending an inquiry to the plurality ofmobile nodes by said application server inquiring whether they want toswitch to the second communication mode to run said network applicationwhen said plurality of mobile nodes are neighboring; downloading andinstalling the network application from said application server to oneof the mobile nodes when all said plurality of mobile nodes agree toswitch to the second communication mode; configuring each mobile nodewith the communication parameters under the second communication modeand switching all said mobile nodes to the second communication mode andcontinuing to run the downloaded and installed network application.

Thus, the present invention provides a system for switching a networkapplication operating in a first communication mode to a secondcommunication mode within a wireless local area network, wherein aplurality of mobile nodes access the network through at least one accesspoint and communicate with at least one application server to obtainvarious network applications provided by said application server in thefirst communication mode; and a plurality of neighboring mobile nodescan communicate with each other directly in the second communicationmode; the system comprising: an application server for providing aplurality of network applications, wherein the application serverincludes an application module and an application agent module; aplurality of access points; a plurality of mobile nodes forcommunicating with the application server through the plurality ofaccess points; each of said plurality of mobile nodes including a clientmodule and a client agent; and a location acquiring apparatus; wherein,in the first communication mode, when the plurality of mobile nodes areaccessing the application server on the network through the accesspoints and running the same network application provided by saidapplication server, said application agent module starting said locationacquiring apparatus to obtain the location information of said pluralityof mobile nodes and judging whether the plurality of mobile nodes areneighboring according to the location information of the mobile nodessent back by the location acquiring apparatus; the application agentmodule sending an inquiry to the plurality of mobile nodes inquiringwhether they want to switch to the second communication mode to run saidnetwork application when the plurality of mobile nodes are neighboring;the application agent module downloading and installing the networkapplication provided by the application server to one of the mobilenodes when all said plurality of mobile nodes agree to switch to thesecond communication mode; the client agent module on each of theplurality of mobile nodes obtaining from the application agent modulethe corresponding parameters of each mobile node in the secondcommunication mode; and the mobile nodes switching to the secondcommunication mode and continuing to run the downloaded and installednetwork application.

Particular embodiments will now be described in connection with thefigures. It should be recognized that embodiments disclosed herein aremerely illustrative. Within the scope of the invention, a person skilledin the field can amend and modify the invention embodiments, and allvariations and equivalents which fall within the range of the conceptsembraced therein.

First of the all, an example of a principle of the present inventionwould be explained. Without loss of generality, the location of allusers can be obtained in infrastructure mode. Then, according to thelocation of the users, some neighboring users who are in the samenetwork application can be switched to Ad-hoc mode together. Throughthis method, WLAN can support more users and reduce the network trafficat the same time. When one of the users in Ad-hoc mode wishes to leavethe network application, the other users will automatically switch theirmobile nodes from Ad-hoc mode to infrastructure mode, recover theiroriginal network configuration, return to the previous networkapplication and wait for new corners to join the network application.

The disclosed method provides the above mentioned functions: whenrunning certain network applications, such as online gaming or internetchatting or other similar network applications using WLAN, the mobilenodes dynamically switch between Ad-hoc mode and infrastructure modeon-demand.

According to one embodiment of the present invention, in infrastructuremode of WLAN, the application server (a server providing online gaming,online chatting, net meetings, etc) accessed by mobile nodessimultaneously runs a network application of an application agent whichis designed according to the present invention. For example, in thenetwork applications such as gaming, chatting or net meeting etc areembedded with an application agent in the manner of software, hardwareor combination of software and hardware. When the application agentfinds that the connections to any AP approach to the maximum capacityand there are still more users trying to access said application server,the application agent then asks a location apparatus to obtain thelocations of the mobile nodes and decides whether these mobile nodes canbe switched to Ad-hoc mode. If yes, the application agent negotiateswith all the mobile nodes which are in the same session. If all themobile nodes agree to switch to Ad-hoc mode, the application agentswitches all the mobile nodes on demand into Ad-hoc mode so that thenetwork workload is reduced and more users are allowed to obtain theservice. Meanwhile, the mobile nodes switching to Ad-hoc mode cancontinue to access the same service in Ad-hoc mode. That is to say,after being switched to Ad-hoc mode, the users continue to use thenetwork applications such as gaming, chatting and net meetingspreviously running in infrastructure mode. When one or more mobile usersin Ad-hoc leave the network application, other users can be switched ondemand back to infrastructure mode and continue to access the sameapplication and wait for new corners to join.

With the popularization of WLAN, the scenario of employing the technicalsolution of the present invention in which mobile nodes automaticallyswitch from infrastructure mode to Ad-hoc mode and continue the previousnetwork application grows quickly. For example, when passengers arewaiting for or in a train, a subway, a bus, or an airplane, they wouldlike to play the network game or chat through the network by the mobiledevices. And some of them can be switched automatically to Ad-hoc modeto decrease others' waiting time when the services approach to themaximum load. Furthermore, when colleagues want to hold a local netmeeting through WLAN, they can be switched automatically frominfrastructure mode to Ad-hoc mode to reduce the network traffic. Sinceall the applications supporting both infrastructure and Ad-hoc modes canuse this method, the potential business value of this method is great.

Obviously, as compared with the common methods using infrastructuremode, the advantages of the method disclosed by the present inventioninclude:

(1) with the same resource, the present invention can support moreusers, and improve QoS;

(2) dynamically switch between infrastructure mode and Ad-hoc mode toreduce the communication traffic;

(3) reduce the waiting time and cost of user; and

(4) increase the income of the providers of network services.

Detailed description to the process of dynamically and automaticallyswitching between infrastructure mode and Ad-hoc mode would be explainedwith reference to the figures. It should be understood that theillustrative embodiments are for the sake of explanation only but notlimitation to the present invention.

Take the Cisco 340 wireless card for example. According to the presentinvention, in order to switch from infrastructure mode to Ad-hoc modewithout loss of connection to the network application, the mobile nodesshould first perform the following operations:

(1) When the mobile node is configured as infrastructure mode, thenetwork configuration thereof would be set up at first. Referring toFIG. 6, it includes some relevant parameters. Parameters such as IPaddress, gateway, DNS server address, and sub net mask, etc., andwireless card configuration would be set up in the Property pageaccording to the present invention. Referring to the sub-pages of“System Parameters” in FIG. 4, it includes four sub-pages of: systemparameters, RF network, Advanced (Infrastructure) as well as NetworkSecurity. In said system parameters sub-page, set up the relevantinformation of the mobile node (that is the client in this illustrativeembodiment), such as client name (in FIG. 4, the client name is YXL),SSID (in FIG. 4, the SSID1 is IBM), network type (in FIG. 4, the networktype is infrastructure type), Power Save Mode (in FIG. 4, the power savemode is configured as CAM, constantly awake mode), and security level,etc. According to the present invention, all information would be storedinto a client agent.

(2) Application agent judges whether the group of mobile nodes whichaccess the same network application in infrastructure mode can switch toAd-hoc mode. If yes, continue with the next step (3); if no, continuewith the judgment of step (2).

(3) Application agent selects a node as the host node for the networkapplication in Ad-hoc mode.

(4) When application agent notifies the mobile nodes to switch frominfrastructure mode to Ad-hoc mode, application agent will uploadrelevant information of client agent and software, including: clientagent module, network parameters configuration of mobile nodes switchinginto Ad-hoc mode and wireless card configuration as well as the networkapplication software and the corresponding sessions that the users runthe application software. The mobile nodes may use static IP address,IPv6 address, or dynamic IP address assigned from DHCP server ininfrastructure mode. According to the present invention, when switchingto Ad-hoc mode, preferably, all addresses should be in a same group,that is to say, their IP addresses should be in one group, i.e.10.1.2.1, 10.1.2.2, 10.1.2.3, 10.1.2.4, etc. in which only the lastdigit of the IP addresses are different, meaning that all these IPaddresses belong to one group. Application agent transfers suitable IPaddress and relevant network parameters, wireless card parameters,application software, to client agent of each mobile node and sends thesession only to the host node.

(5) Application agents on the mobile nodes configure the network andWLAN wireless card according to the parameter obtained and installrelevant software and sessions.

When the client agent set up network parameters, the parameters sent bythe application agent would be used to ensure that the nodes to beswitched are in the same sub net.

The set up of wireless card by client agent includes: set up twoparameters of the system parameters, “network type” and “networksecurity”. Since all the mobile nodes switching to Ad-hoc mode share thesame SSID. it is only needed to set the network type of the wirelesscard as Ad-hoc mode and cancel all security setup.

In FIG. 5, it schematically illustrates the network security sub-page ofthe property of a Cisco 340 wireless card. In this sub-page, accordingto the present invention, the Network Security Type originally set as“LEAP” (Light Extensible Authentication Protocol) will be cancelled.

Then the client agent installs network application when the group ofsaid nodes is transferred to Ad-hoc mode. At this time, except for thehost, the client agents of all other mobile nodes register with theclient agent of the host node and through this host node, the group ofsaid nodes can continue the previous network application together inAd-hoc mode.

(6) If one or more members of this group of mobile nodes leave and as aresult, the network application can not continue to run, the clientagents of the mobile nodes will automatically switch back toinfrastructure mode and continue to access the previous networkapplication on the server and wait for new corners to join, and then toperform the switching again to Ad-hoc mode.

Next is description of the structures and components implementing thepresent invention.

FIG. 7 schematically illustrates a system that communicates in a WLANaccording to the present invention. In this WLAN communication system,only the communication between a mobile user and the application serveris shown schematically. However, skilled persons in this field shouldknow it should also include a plurality of application servers and aplurality of mobile users accessing the application server throughrelevant APs and getting relevant network applications, such as gaming,chatting, net meetings, etc which are executable application software.Referring to FIG. 7, the example it shows includes an application server701, a client 702 and a location apparatus 703, wherein the applicationserver 701 is the server that provides various network applications tousers through WLAN, such as gaming, chatting, and net meetings, etc.Besides, in FIG. 7, there only shows one client, however, it should beknown that one application server can communicate with a plurality ofclients. In application server 701, there should also include a networkapplication module 7011 which preferably includes various networkapplications, such as the executable software like gaming, chatting, netmeetings, etc. The application server 701 also includes an applicationagent module 7012 which preferably is executable software, or hardwareembedded with software or combination of software and hardware runningon the application server. Application agent module 7012 can beassociated with application module 7011. It can be standalone orembedded into application software. The functions of the applicationagent module 7012 will be described in detail later. In client 702,there is a client module 7021 and a client agent module 7022, whereinthe client module 7021 and client agent module 7022 are also associated.The local apparatus 703 in FIG. 7 is standalone but it can also beembedded into the module on the application server. In FIG. 7, client702 accesses application server 701 through APs and accesses the variousnetwork applications provided by the server, i.e. executable softwarelike gaming, chatting, net meetings, etc. According to the presentinvention, location apparatus 703 gets the location information ofclient 702 and informs the application agent module 7012 of the locationinformation. Meanwhile, if application agent module 7012 finds there isno client agent installed in client, application agent module 7012 willautomatically upload the client agent for client, retrieves informationof the other players from application and judges whether these playerscould be switched to Ad-hoc mode. It can also negotiate with clientagent module 7022 and manage the auto-switching process for application.

(1) Location Apparatus

The location apparatus 703 can be a standalone or an embedded apparatus.The function of location apparatus 703 is to get the location of themobile nodes. Several methods or apparatus can be used here. Thesimplest way is to use the coordination of authentication server and APto get the location of the mobile nodes. This is the common sense inthis field. Authentication server can validate the user's identity, andobtain the user's IP address and associated AP. Because the AP is set ona static location, and the topology of APs is known in prior and thelocation of each mobile node from different AP varies and the locationof APs is different, the signal strength of the mobile nodes obtained bythe different APs varies. The location of the mobile nodes can befigured out with the signal strength of three APs (triangularizationusing signal strength). The location of AP can also be used as thelocation information of users to judge whether they are neighboring. Forthose which are neighboring, triangularization of signal strength can befurther used. Special location apparatus can also be used, such as GPS,mobile nodes equipped with GPS receiver send location information toapparatus through WLAN.

(2) Application Server

Application server 701 for example can be the software platform fornetwork gaming software or net meeting/chatting software installed onapplication agent module 7012. According to the present invention, theapplication server can be divided into two parts. However, skilledperson in this field may know, this division is for the sake ofexplanation only and the present invention is not limited to thissituation:

Application module 7011: application module 7011 shares its game sessioninformation with the application agent module 7012 and allows theapplication agent module 7012 to access them, such as deleting thesession information of the mobile nodes which have switched to Ad-hocmode.

Application agent module 7012: according to the present invention,application agent module 7012 can be a standalone component or embeddedcompletely into the application module 7011. Application agent module7012 for example can also include:

Location listener (not shown in figures): this location listener is usedto get location information of mobile nodes from the location apparatus703;

Application management proxy (not shown in figures): it can get gamesession information from the application module 7011 and manage them,such as deleting session information of the users who have been changedto Ad-hoc mode, negotiating with client agent module 7022, selectinghost from clients, and downloading software, etc;

Decision apparatus (not shown in figures): when the location apparatus703 is some kind of special location apparatus, it can decide whethersome clients can be changed to Ad-hoc mode by computing the distancebetween them; the decision apparatus used herein can make such decisionby employing similar methods as the location apparatus would use;therefore detailed explanations would be omitted.

(3) Client

Client 702, namely a mobile node is equipped with wireless card and canaccess network through wireless location area network. It can alsoaccess the services provided by the application server, downloadsoftware from the application server, etc. Mobile node can be a laptop,a PDA, etc. A client agent module 7022 is installed on it. The clientcan also be divided into two parts as explained below: pure clientmodule and client agent module. However, skilled person in this fieldmay know that this division is for the sake of explanation only and thepresent invention is not limited to the situation:

Client module 7021: it includes the module for host client and themodule for other common clients. The host client module represents themost powerful mobile node among all nodes switching to Ad-hoc mode.Except for the functions that common client could perform, the hostclient module can still download, run or upload game host software andmanage the game in Ad-hoc mode.

Client agent module 7022: it stores the hardware and softwareconfiguration, such as CPU, HD, memory etc, negotiates with theapplication agent module 7022, saves old network configuration, andreconfigures the client network configuration. The client agent module7022 can communicate with other agents in Ad-hoc mode, and cancommunicate with the application agent in Infrastructure mode.

(4) Access Point: through it, the mobile node (namely the client) canconnect to the application server and get the services from theapplication server.

Next is the workflow description taking network game as an example. Itshould be understood that, for the sake of description, thisillustrative embodiment selects network gaming scenario for descriptionbut other scenarios can also be considered, such as chatting, netmeetings, etc. for the description of the workflow chart of the presentinvention.

(1) According to the present invention, at first, an application agentis installed in the application server, and the application is runningin the server side to provide application programs such as networkinggaming, chatting, or e-meeting etc., and the application agent gets hostsoftware and hardware configuration requirements from the application;

(2) For example, Clients C1-C4 enter the hot spot, associate the AP andbegin to launch the network game. Before he/she plays the network game,the server checks whether the clients has installed client agent. Ifnot, automatically upload and install it on the client; if yes, theapplication agent gets user preference and the information of pastpartners, initiates the game for these users.

(3) Suppose that Client 1 is the host in the game. Clients 1-4 can usemobile IP, IPv6 or get dynamic IP address through DHCP server. Client1-4 agents store their network configuration in infrastructure mode.

(4) The application agent gets access information from theauthentication server and find that some AP's work load is too heavy,for example, AP1 can only support 30 users and now 28 users haveassociated it, the threshold of workload can be set up by the serveradministrator;

(5) The application agent starts the location apparatus to get thelocations of the mobile nodes and the location apparatus sends thelocation information of the mobile nodes to the application agent.

(6) The application agent gets to know that some users are playing thegame from the application server, for example, C1-C4 are playing in agame. It can further judge whether C1-C4 can change to Ad-hoc modeaccording to their locations. If not, let them continue to work atinfrastructure mode or if location information indicates that users cannot switch to Ad-hoc mode, application agent can firstly send a messageto client agent informing users of changing locations to other places sothat they can switch to Ad-hoc mode to lower costs. Otherwise, go tonext step;

(7) The application agent gets the software and hardware configurationof the clients who can be switched to Ad-hoc, decides whether some ofthem can be the host; if not, let them continue to work atinfrastructure mode. The decision principles for the host include:

Check the software and hardware configuration of each client, such asCPU, hard disk, memory, software platform, judge whether it can be thehost;

If more than one client can be the host, select the one with the bestconfiguration as the host; here best means faster CPU, bigger memory,bigger hard disk and higher version software platform;

If one client has installed host software, it should be the host.

(8) If the host has been selected, the application agent negotiates withall client agents: ask them whether they would like to work in Ad-hocmode to reduce the cost; if C1-C4 all agree to switch to Ad-hoc mode,C1-C4 agents begin to work according to process (9) below; otherwise,let them continue to work at infrastructure mode.

(9) The application agent uploads suitable game software to C1-C4, if C4is selected as the host, it also needs to be uploaded the session andinstall it.

(10) The application agent assigns the C1-C4 with static IP addresses,subnet mask and SSID and deletes their session information fromapplication;

(11) Each client agent stores its user's preference, that is, the gamehe/she is playing and its IP address, AP, the IP address of thepartners.

(12) The Client agent receives the client configuration from theapplication agent, stores its old network configuration, releases theold IP address, and reconfigures the client with the new parameter;

(13) C4 invites C1-C3 and they continue the session;

(14) When the client agent detects that one of C1-C4 leaves the game,the client agent releases Ad-hoc mode, that is, it reconfigures thenetwork parameters and wireless card parameters and reconnects toapplication;

(15) If the application checks that the client has installed clientagent, then it checks the client preference to ensure it is set ontoday. After that, it selects the suitable software for the client, andfinds the other partners. And finally, it helps them to re-compose thegame. The re-composed clients will wait for the new corner to join theirgame.

(16) The client agent provides tools to remove the uploaded software.

Referring to FIG. 8, it schematically shows the switching frominfrastructure mode to Ad-hoc mode according to the present inventionfor communication. As illustrated in FIG. 8, a first Ad-hoc networkgroup 1 includes four clients, C1, C2, C3, and C4. These four clientscommunicate with an application server (same as the server in FIG. 7)through an access point 802. Similarly, it also illustrates a secondAd-hoc network group 2 with four clients communicating with applicationserver 801 through a second access point. It can also include otherAd-hoc network groups which communicate with application server 801. Forthe sake of clarity, they are not described here in details. Thecommunication system in FIG. 8 also includes an authentication server803. It is used to get IDs of authenticated users and IP addresses ofusers and associated APs (may also participate in obtaining thelocations of mobile nodes) in the process of switching betweeninfrastructure mode and Ad-hoc mode. This is the common sense of thisfield. In addition, in the communication system in FIG. 8, a router 804is also provided which is well known in this field.

FIG. 9 and FIG. 10 show the steps of executing the application agentprocess on the application server and of executing client agent processon the client respectively.

Referring to FIG. 9, it shows the work flow of the operation executed byapplication agent on the application server.

When application server runs an application providing such as networkgaming, net-chatting or net meetings, etc, firstly, in step S901, anapplication agent AA installed on the said application server gets thehost software and hardware configuration requirements in Ad-hoc modefrom the running application.

When users access to network and join the network application providedby the application server, for example when Client C1-C4 launch anetwork game through the same access point in infrastructure mode,before the users start playing games, at step S902, application agentwill judge whether associated clients, namely clients C1-C4, have beeninstalled client agent. If no, the result of judgment at step S902 is NOand the process moves to step S903, application agent uploads andinstalls client agent on the clients automatically. Otherwise, if theresult of step S902 is YES, that is, the client agent is installed onclients. The process moves to S904. The application agent gets theinformation of the users' preference and the information on pastpartners and starts the users' games.

Next, when the client agent is installed at step S903, or the userprepares to start the network game at step S904, the application agentgets relevant information from the authentication server at step 905.For example, verifying the user' ID from the authentication server andgetting the IP addresses of the user' and associated AP.

At step S906, judge whether the access point is overload, that is, judgewhether the number of users supported by current access point hasexceeded the maximum it can support. If the result of step S906 is NO,the process will return to step S905 and continue to get relevantinformation from the authentication server. If the result of judgment ofstep S906 is YES, the current access point should be regarded asoverloaded. Then the process will go to step S907.

At step S907, the application agent starts a location apparatus andobtains the location information of the clients. For example, ClientsC1-C4 can use mobile IP, IPv6 or get dynamic IP addresses from DHCPserver. Here, the location of the mobile nodes can be obtained inseveral ways or with several apparatus. The simplest way is to get thelocation of the mobile nodes through authentication server and thetriangularization of the signal strength, which is the common sense inthis field. The users' location can also be obtained in other ways, suchas GPS technology.

Next, at step 908, the process judges whether some users can switch toAd-hoc mode. If YES, the process moves to step S910. Otherwise, if theresult is NO, the process then moves to step S909. Application agent canprompt client agent of the location where the mobile nodes can move toand in which location the mobile nodes can switch to Ad-hoc mode tolower costs. Then the application agent returns to step S907 to continueto launch location apparatus to obtain the location information of themobile nodes.

In step S910, further judgment is made on whether it is possible toselect one from the said users as the host in Ad-hoc mode. If there isno such a client, let them continue to work in infrastructure mode. Theprinciple for judging the host in Ad-hoc mode includes:

checking the software and hardware configuration of each client, suchas, CPU, Hard Disk, memory, software platform and judge whether they canbe the host in Ad-hoc mode;

If more than one client can be the host in Ad-hoc mode, select the onewith the best configuration as the host in Ad-hoc mode; wherein the bestconfiguration means: faster CPU, bigger memory, bigger hard disk andhigher version software platform;

If one client has been installed host software, it should be selected asthe host in Ad-hoc mode.

If the result of step S910 shows that at least one from the currentclients can be selected as the host, the process then goes to step S911.Otherwise, the application agent returns to step S907 and continues tolaunch location apparatus to get the location information of the mobilenodes.

In step S911, application agent negotiates with all of the currentclients, such as client C1-C4, asking them whether they wish to work inAd-hoc type network; if Client C1-C4 all agree to switch to Ad-hoc mode,then the process goes to step S912. Otherwise, application agent returnsto step S907 and continues to launch location apparatus to obtainlocation information of the mobile nodes.

In step S912, application agent further obtains information of sessionsbetween the application server and the clients and information aboutgames from the application server.

Then the process moves to step S913. The application agent uploadssuitable game software to client C1-C4. If client C4 is selected as ahost, the application agent further uploads the session between theclients and application server and installs the session in client 4. IfClients C1-C4 don't agree to switch to Ad-hoc mode, let C1-C4 continueto work in infrastructure mode.

After clients C1-C4 choose to switch to Ad-hoc mode, in step S914,application agent assigns C1-C4 with static IP addresses and networkparameters such as subnet mask and SSID whilst deletes sessioninformation and network application program information from theapplication.

Through the above mentioned operation, the dynamic switching frominfrastructure mode to Ad-hoc mode is fulfilled, whereby the benefitsare achieved as follows: (1) with the same resource, the present methodcan support more users, and improve QoS; (2) dynamically switch betweeninfrastructure mode and Ad-hoc mode to reduce the communication traffic;(3) reduce the waiting time and cost of user; and (4) increase theincome of the provider of network services.

Referring to FIG. 10, it illustrates the flow chart of the operationperformed by client agent on the clients.

When a user wishes to join, for example an application such as networkgame, firstly in step S1001, this user will connect his/her client withthe application server which provides network games through an AP ininfrastructure mode and open a network application.

In step S1002, before the user starts the network game, the applicationserver has a check on the client to see if the client is installed witha client agent. If this client has been already installed the clientagent, then it is allowed to start a game. Otherwise, the process movesto step S1003 where the application server automatically installs theclient agent on the client and said client agent obtains relevant clientsoftware and hardware configuration in step S1004.

Next, in step S1005, the client starts to officially access the networkapplication. In the process of client participating in networkapplication, when the application server finds that the number of userssupported by the current AP has exceeded the maximum it can support, theapplication server will prompt users of whether they wish to switch toAd-hoc mode. That is in step S1006, for example, a window will pop up onthe client's screen asking the users whether they agree to switch toAd-hoc mode. Likewise, other methods can be used to ask whether theusers wish to switch i.e. in audio and visual forms or rolling bars. Ifthe users do not agree to switch, let said users be in infrastructuremode and continue their game; however, if the users agree to switch,then the process moves to step S1007. The client agent stores theparameters of network and wireless card and the users' preference, suchas the game played and IP addresses, AP and IP addresses of thepartners.

Next, in step S1008, suitable software is installed in the clients.Wherein said software is the network application software to beinstalled on the host in Ad-hoc mode; and the client agent reconfiguresthe network of the clients to work in Ad-hoc mode.

Thus all clients of one group are configured, such as Client C1-C4.Then, in Ad-hoc mode, continue the games played by client C1-C4 ininfrastructure mode, step S1009.

When in step S1010, the host in Ad-hoc mode detects that some usersleave, the process moves to step S1011. The host in Ad-hoc mode notifiesother client agents to release Ad-hoc mode and reconfigure networkparameters and wireless card parameters to recover infrastructure modeand return to the original network application. Preferably, the clientagent provides tools to delete the uploaded software.

From the above mentioned description, it can be known that the wholework process is automatic. When switching between infrastructure modeand Ad-hoc mode, the users will feel slightly slow. What the users needto do is to agree to switch to Ad-hoc mode to reduce cost.

Hence, the benefits of the method and system based on the presentinvention to switch between the different modes of wireless localnetwork are:

(1) For Airport: Airport can charge the users who work in infrastructuremode more money and charge the users who work in Ad-hoc mode less money.It can also add switching principles, for example, unless AP'sassociation to the network arrives at maximum load, the switch functionwill not start up so that the airport can obtain maximum profit with thesame resource. Also, the airport improves the quantity of service andreduces the network traffic.

(2) For users: the proposed method reduces waiting time of the use andthus increases customer satisfaction. A user can freely make his/herchoice: switch to Ad-hoc mode and reduce the cost; or continue oninfrastructure mode.

Various embodiments for implementing the method and system of switchingbetween two different modes of wireless local area network according tothe present invention have been described in detail above in combinationwith the figures thereof. However the described embodiments are merelyfor the purpose of exemplary. Various changes or modifications may bemade by the skilled persons without departing from the sprit and scopeof the invention. Accordingly, the present invention is not limited tothe illustrative embodiments except as specified in the attached claims.The description above focuses on these particular disclosed embodiments,however, it should be understood that the present invention is notlimited to these.

Thus, the present invention can be realized in hardware, software, or acombination of hardware and software. It may be implemented as a methodhaving steps to implement one or more functions of the invention, and/orit may be implemented as an apparatus having components and/or means toimplement one or more steps of a method of the invention described aboveand/or known to those skilled in the art. A visualization tool accordingto the present invention can be realized in a centralized fashion in onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system—or other apparatus adapted for carrying out the methodsand/or functions described herein—is suitable. A typical combination ofhardware and software could be a general purpose computer system with acomputer program that, when being loaded and executed, controls thecomputer system such that it carries out the methods described herein.The present invention can also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which—when loaded in a computersystem—is able to carry out these methods. Methods of this invention maybe implemented by an apparatus which provides the functions carrying outthe steps of the methods. Apparatus and/or systems of this invention maybe implemented by a method that includes steps to produce the functionsof the apparatus and/or systems.

Computer program means or computer program in the present contextinclude any expression, in any language, code or notation, of a set ofinstructions intended to cause a system having an information processingcapability to perform a particular function either directly or afterconversion to another language, code or notation, and/or afterreproduction in a different material form.

Thus, the invention includes an article of manufacture which comprises acomputer usable medium having computer readable program code meansembodied therein for causing one or more functions described above. Thecomputer readable program code means in the article of manufacturecomprises computer readable program code means for causing a computer toeffect the steps of a method of this invention. Similarly, the presentinvention may be implemented as a computer program product comprising acomputer usable medium having computer readable program code meansembodied therein for causing a function described above. The computerreadable program code means in the computer program product comprisingcomputer readable program code means for causing a computer to affectone or more functions of this invention. Furthermore, the presentinvention may be implemented as a program storage device readable bymachine, tangibly embodying a program of instructions executable by themachine to perform method steps for causing one or more functions ofthis invention.

It is noted that the foregoing has outlined some of the more pertinentobjects and embodiments of the present invention. This invention may beused for many applications. Thus, although the description is made forparticular arrangements and methods, the intent and concept of theinvention is suitable and applicable to other arrangements andapplications. It will be clear to those skilled in the art thatmodifications to the disclosed embodiments can be effected withoutdeparting from the spirit and scope of the invention. The describedembodiments ought to be construed to be merely illustrative of some ofthe more prominent features and applications of the invention. Otherbeneficial results can be realized by applying the disclosed inventionin a different manner or modifying the invention in ways known to thosefamiliar with the art.

What is claimed is:
 1. A method comprising switching a networkapplication operating in a first communication mode to a secondcommunication mode within a wireless local area network, wherein aplurality of mobile nodes access the network through at least one accesspoint and communicate with at least one application server to obtain atleast one network application provided by said application server in thefirst communication mode; and a plurality of neighboring mobile nodescan communicate with each other directly in the second communicationmode; the step of switching comprising the steps of: when the pluralityof mobile nodes are accessing the application server on the networkthrough the access points and running the same network applicationprovided by said application server in the first communication mode,judging whether the plurality of mobile nodes are neighboring accordingto location information of each of said mobile nodes; sending an inquiryto the plurality of mobile nodes by said application server inquiringwhether the plurality of mobile nodes want to switch to the secondcommunication mode to run said network application when said pluralityof mobile nodes are neighboring; downloading and installing the networkapplication from said application server to one of the mobile nodes whenall said plurality of mobile nodes agree to switch to the secondcommunication mode; configuring each mobile node with communicationparameters under the second communication mode; and switching all saidmobile nodes to the second communication mode and continuing to run adownloaded and installed network application.
 2. The method of claim 1,wherein, the first communication mode is an Infrastructure mode and thesecond communication mode is a peer to peer Ad-hoc communication mode.3. The method of claim 1, further comprising one of said applicationserver and an authentication server, obtaining the location informationof the mobile nodes, session information between the mobile nodes andsaid application server and the associated information about the networkapplication.
 4. The method of claim 1, wherein the step of judgingwhether the plurality of mobile nodes are neighboring according to thelocation information of the mobile nodes further comprising the stepsof, using at least one of the following methods to judge: a) obtainingthe location of the mobile nodes through the coordination of theauthentication server and access point; judging whether the plurality ofmobile nodes are neighboring by the triangularization of the signalstrength according to various distances between mobile nodes anddifferent access points; b) judging whether said mobile nodes areadjacent firstly by using the location of the access point as the userlocation information; and for the adjacent mobile nodes, further usingthe triangularization of signal strength to judge whether they areneighboring; and c) sending location information through wireless localarea network by using special location apparatus thereby to judgewhether the mobile nodes are neighboring.
 5. The method of claim 1,further comprising: obtaining the host configuration requirements forthe second communication mode from said network application of theapplication server; selecting one as the host node from the plurality ofmobile nodes which will switch to the second communication mode;downloading and installing the network application provided by theapplication server on said host node, and receiving and installing bysaid host node the session concerning said network application from saidapplication server.
 6. The method of claim 5, wherein the step ofselecting one as the host node from the plurality of mobile nodes whichwill switch to the second communication mode comprising using one of thefollowing methods: checking the configuration of each mobile node tojudge whether it can be used as the host node in the secondcommunication mode; selecting the one with the best configuration as thehost of the second communication mode if there is more than one mobilenodes can be used as the host node of the second communication mode,wherein the best configuration means: the fastest CPU, bigger memory,bigger hard disk and higher version of software platform; and selectingthe mobile node as the host of the second communication mode if it isinstalled the host software.
 7. The method of claim 5, furthercomprising causing other mobile nodes to register with said host nodewhen switching to the second communication mode.
 8. The method of claim1, wherein the step of configuring each mobile node with thecommunication parameters under the second communication mode comprisingthe step of: configuring each mobile node with IP address, networkparameters and wireless card parameters.
 9. The method of claim 1,further comprising setting and saving the network configuration for theplurality of mobile nodes when configured to operate in the firstcommunication mode.
 10. The method of claim 1, further comprising saidplurality of mobile nodes using static IP address or IPv6 address, ordynamic IP address assigned by the DNS server of the first communicationmode; and judging whether addresses of the plurality of mobile nodes arein a same group when prepared to switch to the second communicationmode.
 11. The method of claim 1, further comprising: judging whethersaid mobile nodes are installed a client agent; said application serverautomatically uploading and installing the client agent for the mobilenodes when the client agent is not installed in the mobile nodes;transmitting suitable IP address, corresponding network parameters,wireless card parameters, application software to the client agent oneach of the plurality of mobile node; and the client agent on each ofplurality of mobile nodes setting the network and wireless card andinstalling corresponding software and session according to theparameters obtained.
 12. The method of claim 1, further comprisingcausing said mobile nodes automatically switch back to infrastructuremode to re-access the previous network application on the applicationserver when the network application is running in the secondcommunication mode, and one or more mobile nodes leave.
 13. A system forswitching a network application operating in a first communication modeto a second communication mode within a wireless local area network,wherein a plurality of mobile nodes access the network through at leastone access point and communicate with at least one application server toobtain various network applications provided by said application serverin the first communication mode; and a plurality of neighboring mobilenodes can communicate with each other directly in the secondcommunication mode; the system comprising: an application server forproviding a plurality of network applications, wherein the applicationserver includes an application module and an application agent module; aplurality of access points; a plurality of mobile nodes forcommunicating with the application server through the plurality ofaccess points; each of said plurality of mobile nodes including a clientmodule and a client agent; and a location acquiring apparatus; wherein,in the first communication mode, when the plurality of mobile nodes areaccessing the application server on the network through the accesspoints and running the same network application provided by saidapplication server, said application agent module starting said locationacquiring apparatus to obtain the location information of said pluralityof mobile nodes and judging whether the plurality of mobile nodes areneighboring according to the location information of the mobile nodessent back by the location acquiring apparatus; the application agentmodule sending an inquiry to the plurality of mobile nodes inquiringwhether they want to switch to the second communication mode to run saidnetwork application when the plurality of mobile nodes are neighboring;the application agent module downloading and installing the networkapplication provided by the application server to one of the mobilenodes when all said plurality of mobile nodes agree to switch to thesecond communication mode; the client agent module on each of theplurality of mobile nodes obtaining from the application agent modulecorresponding parameters of each mobile node in the second communicationmode; and the mobile nodes switching to the second communication modeand continuing to run the downloaded and installed network application.14. The system of claim 13, wherein the first communication mode is anInfrastructure mode and the second communication mode is a peer to peerAd-hoc communication mode.
 15. The system of claim 13, wherein thelocation apparatus is further configured to: obtain, by said applicationserver or an authentication server, the location information of themobile nodes, session information between the mobile nodes and saidapplication server and the associated information about the networkapplication.
 16. The system of claim 13, wherein the application agentmodule further comprising a judging means for judging whether theplurality of mobile nodes are neighboring, using at least one of thefollowing methods: a) obtaining the location of the mobile nodes throughthe coordination of the authentication server and the access point;judging whether the plurality of mobile nodes are neighboring by thetriangularization of the signal strength according to various distancesbetween mobile nodes and different access points; b) judging whethersaid mobile nodes are adjacent firstly by using the location of theaccess point as the user location information; and for the adjacentmobile nodes, further using the triangularization of signal strength tojudge whether they are neighboring; or c) sending location informationthrough wireless local area network by using special location apparatusthereby to judge whether the mobile nodes are neighboring.
 17. Thesystem of claim 13, wherein the application agent module is furtherconfigured to: obtain the host configuration requirements for the secondcommunication mode from said network application of the applicationserver; select one as the host node from the plurality of mobile nodeswhich will switch to the second communication mode; download and installthe network application provided by the application server on said hostnode, and communicate with the client agent module on the host node sothat the host node receive and install the session concerning saidnetwork application from said application server.
 18. The system ofclaim 17, wherein the application agent module is also configured toselect one as the host node from the plurality of mobile nodes that willswitch to the second communication mode using one of the followingmethods: checking the configuration of each mobile node to judge whetherit can be used as the host node in the second communication mode;selecting the one with the best configuration as the host of the secondcommunication mode if there is more than one mobile nodes can be used asthe host node of the second communication mode, wherein the bestconfiguration means: the fastest CPU, bigger memory, bigger hard diskand higher version of software platform; selecting the mobile node asthe host of the second communication mode if it is installed the hostsoftware.
 19. The system of claim 17, wherein the client agent module onthe host node is further configured to: cause other mobile nodes toregister with said host node when switching to the second communicationmode.
 20. The system of claim 13, wherein communication parametersobtained by each client agent module under the second communication modecomprising: the IP address for each mobile node, network parameters andwireless card parameters.
 21. A system of claim 13, wherein each clientagent module is further configured to set and save the networkconfiguration for the plurality of mobile nodes when configured tooperate in the first communication mode.
 22. The system of claim 13,wherein, said plurality of mobile nodes using static IP address or IPv6address, or dynamic IP address assigned by the DNS server of in thefirst communication mode; and the application agent module is configuredto judge whether the addresses of the plurality of mobile nodes are in asame group when prepared to switch to the second communication mode. 23.The system of claim 13, wherein the application agent module is furtherconfigured to: judge whether said mobile nodes are installed a clientagent; automatically upload and install the client agent for the mobilenodes when the client agent is not installed in the mobile nodes;transmit suitable IP address, corresponding network parameters, wirelesscard parameters, application software to the client agent on each of theplurality of mobile node; and the client agent on each of plurality ofmobile nodes is configured to set the network and wireless card, and toinstall corresponding software and sessions according to parametersobtained.
 24. The system of claim 13, wherein each client agent moduleis configured to cause said mobile nodes automatically switch back toinfrastructure mode to re-access the previous network application on theapplication server when the network application is running in the secondcommunication mode, and one or more mobile nodes leave.
 25. An articleof manufacture comprising a non-transitory computer usable medium havingcomputer readable program code embodied therein for causing switching ofa network application, the computer readable program code in saidarticle of manufacture comprising steps of: switching a networkapplication operating in a first communication mode to a secondcommunication mode within a wireless local area network, wherein aplurality of mobile nodes access the network through at least one accesspoint and communicate with at least one application server to obtain atleast one network application provided by said application server in thefirst communication mode; and a plurality of neighboring mobile nodescan communicate with each other directly in the second communicationmode; the step of switching comprising the steps of: when the pluralityof mobile nodes are accessing the application server on the networkthrough the access points and running the same network applicationprovided by said application server in the first communication mode,judging whether the plurality of mobile nodes are neighboring accordingto location information of each of said mobile nodes; sending an inquiryto the plurality of mobile nodes by said application server inquiringwhether the plurality of mobile nodes want to switch to the secondcommunication mode to run said network application when said pluralityof mobile nodes are neighboring; downloading and installing the networkapplication from said application server to one of the mobile nodes whenall said plurality of mobile nodes agree to switch to the secondcommunication mode; configuring each mobile node with communicationparameters under the second communication mode; and switching all saidmobile nodes to the second communication mode and continuing to run adownloaded and installed network application.
 26. A computer programproduct comprising a non-transitory computer usable medium havingcomputer readable program code means embodied therein for causing aswitching of a network application operating in a first communicationmode to a second communication mode within a wireless local areanetwork, the computer readable program code means in said computerprogram product comprising computer readable program code means forcausing a computer to effect the functions of claim 13.